First commit library created

idDHT11.cpp

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+/*
+	FILE: 		idDHT11.cpp
+	VERSION: 	0.1
+	PURPOSE: 	Interrupt driven Lib for DHT11 with Arduino.
+	LICENCE:	GPL v3 (http://www.gnu.org/licenses/gpl.html)
+	DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
+	
+	Based on DHT11 library: http://playground.arduino.cc/Main/DHT11Lib
+*/
+
+#include "idDHT11.h"
+#define DEBUG_IDDHT11
+
+idDHT11::idDHT11(int pin, int intNumber,void (*callback_wrapper)()) {
+	init(pin, intNumber,callback_wrapper);
+}
+
+void idDHT11::init(int pin, int intNumber, void (*callback_wrapper) ()) {
+	this->intNumber = intNumber;
+	this->pin = pin;
+	this->isrCallback_wrapper = callback_wrapper;
+	hum = 0;
+	temp = 0;
+	pinMode(pin, OUTPUT);
+	digitalWrite(pin, HIGH);
+	state = STOPED;
+	status = IDDHTLIB_ERROR_NOTSTARTED;
+}
+
+int idDHT11::acquire() {
+	if (state == STOPED || state == ACQUIRED) {
+		
+		//set the state machine for interruptions analisis of the signal
+		state = RESPONSE;
+		
+		// EMPTY BUFFER and vars
+		for (int i=0; i< 5; i++) bits[i] = 0;
+		cnt = 7;
+		idx = 0;
+		hum = 0;
+		temp = 0;
+	
+		// REQUEST SAMPLE
+		pinMode(pin, OUTPUT);
+		digitalWrite(pin, LOW);
+		delay(18);
+		digitalWrite(pin, HIGH);
+		delayMicroseconds(40);
+		pinMode(pin, INPUT);
+		
+		// Analize the data in an interrupt
+		us = micros();
+		attachInterrupt(intNumber,isrCallback_wrapper,FALLING);
+		
+		return IDDHTLIB_ACQUIRING;
+	} else
+		return IDDHTLIB_ERROR_ACQUIRING;
+}
+void idDHT11::isrCallback() {
+	int newUs = micros();
+	int delta = (newUs-us);
+	us = newUs;
+	if (delta>6000) {
+		status = IDDHTLIB_ERROR_TIMEOUT;
+		state = STOPED;
+		detachInterrupt(intNumber);
+		return;
+	}
+	switch(state) {
+		case RESPONSE:
+			if(delta<25)
+				return; //do nothing, it started the response signal
+			if(125<delta && delta<170) {
+				state = DATA;
+			} else {
+				detachInterrupt(intNumber);
+				status = IDDHTLIB_ERROR_TIMEOUT;
+				state = STOPED;
+			}
+			break;
+		case DATA:
+			if(delta<10) {
+				detachInterrupt(intNumber);
+				status = IDDHTLIB_ERROR_DELTA;
+				state = STOPED;
+				// return;
+			} else if(60<delta && delta<135) { //valid in timing
+				if(delta>90) //is a one
+					bits[idx] |= (1 << cnt);
+				if (cnt == 0) {  // whe have fullfilled the byte, go to next
+						cnt = 7;    // restart at MSB
+						if(idx++ == 4) {      // go to next byte, if whe have got 5 bytes stop.
+							detachInterrupt(intNumber);
+							// WRITE TO RIGHT VARS
+							// as bits[1] and bits[3] are allways zero they are omitted in formulas.
+							hum    = bits[0]; 
+							temp = bits[2]; 
+							uint8_t sum = bits[0] + bits[2];  
+							if (bits[4] != sum) {
+								status = IDDHTLIB_ERROR_CHECKSUM;
+								state = STOPED;
+							} else {
+								status = IDDHTLIB_OK;
+								state = ACQUIRED;
+							}
+							break;
+						}
+				} else cnt--;
+			} else {
+				detachInterrupt(intNumber);
+				status = IDDHTLIB_ERROR_TIMEOUT;
+				state = STOPED;
+			}
+			break;
+		default:
+			break;
+	}
+}
+bool idDHT11::acquiring() {
+	if (state != ACQUIRED && state != STOPED)
+		return true;
+	return false;
+}
+int idDHT11::getStatus() {
+	return status;
+}
+float idDHT11::getCelsius() {
+	IDDHT11_CHECK_STATE;
+	return temp;
+}
+
+float idDHT11::getHumidity() {
+	IDDHT11_CHECK_STATE;
+	return hum;
+}
+
+float idDHT11::getFahrenheit() {
+	IDDHT11_CHECK_STATE;
+	return temp * 1.8 + 32;
+}
+
+float idDHT11::getKelvin() {
+	IDDHT11_CHECK_STATE;
+	return temp + 273.15;
+}
+
+// delta max = 0.6544 wrt dewPoint()
+// 5x faster than dewPoint()
+// reference: http://en.wikipedia.org/wiki/Dew_point
+double idDHT11::getDewPoint() {
+	IDDHT11_CHECK_STATE;
+	double a = 17.271;
+	double b = 237.7;
+	double temp_ = (a * (double) temp) / (b + (double) temp) + log( (double) hum/100);
+	double Td = (b * temp_) / (a - temp_);
+	return Td;
+	
+}
+// dewPoint function NOAA
+// reference: http://wahiduddin.net/calc/density_algorithms.htm 
+double idDHT11::getDewPointSlow() {
+	IDDHT11_CHECK_STATE;
+	double A0= 373.15/(273.15 + (double) temp);
+	double SUM = -7.90298 * (A0-1);
+	SUM += 5.02808 * log10(A0);
+	SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
+	SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
+	SUM += log10(1013.246);
+	double VP = pow(10, SUM-3) * (double) hum;
+	double T = log(VP/0.61078);   // temp var
+	return (241.88 * T) / (17.558-T);
+}
+// EOF

idDHT11.h

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+/*
+	FILE: 		idDHT11.h
+	VERSION: 	0.1
+	PURPOSE: 	Interrupt driven Lib for DHT11 with Arduino.
+	LICENCE:	GPL v3 (http://www.gnu.org/licenses/gpl.html)
+	DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf
+	
+	Based on DHT11 library: http://playground.arduino.cc/Main/DHT11Lib
+*/
+
+
+#ifndef idDHT11_H__
+#define idDHT11_H__
+
+#if defined(ARDUINO) && (ARDUINO >= 100)
+#include <Arduino.h>
+#else
+#include <WProgram.h>
+#endif
+
+#define IDDHT11LIB_VERSION "0.1"
+
+// state codes
+#define IDDHTLIB_OK				0
+#define IDDHTLIB_ACQUIRING		1
+#define IDDHTLIB_ACQUIRED		2
+#define IDDHTLIB_RESPONSE_OK	3
+
+// error codes
+#define IDDHTLIB_ERROR_CHECKSUM		-1
+#define IDDHTLIB_ERROR_TIMEOUT		-2
+#define IDDHTLIB_ERROR_ACQUIRING	-3
+#define IDDHTLIB_ERROR_DELTA		-4
+#define IDDHTLIB_ERROR_NOTSTARTED	-5
+
+#define IDDHT11_CHECK_STATE		if(state == STOPED)													\
+									return status;													\
+								else if(state != ACQUIRED)				\
+									return IDDHTLIB_ERROR_ACQUIRING;
+									
+class idDHT11
+{
+public:
+	idDHT11(int pin, int intNumber,void (*isrCallback_wrapper)());
+    void init(int pin, int intNumber,void (*isrCallback_wrapper)());
+	void isrCallback();
+	int acquire();
+	float getCelsius();
+	float getFahrenheit();
+	float getKelvin();
+	double getDewPoint();
+	double getDewPointSlow();
+	float getHumidity();
+	bool acquiring();
+	int getStatus();
+	
+private:
+	
+	void (*isrCallback_wrapper)(void);
+	
+	enum states{RESPONSE=0,DATA=1,ACQUIRED=2,STOPED=3,ACQUIRING=4};
+	volatile states state;
+	volatile int status;
+	volatile byte bits[5];
+	volatile byte cnt;
+	volatile byte idx;
+	volatile int us;
+	int intNumber;
+	int pin;
+	volatile float hum;
+	volatile float temp;
+};
+#endif // idDHT11_H__